| No | Pattern | Freq | Relations |
|---|---|---|---|
| 1 | [verb] n't know for certain | 7 |
|
| 2 | do n't know for certain | 7 |
|
| 3 | do n't know for certain | 5 |
|
| 4 | [vb base] n't know for certain | 5 |
|
